Question sentence generating device and computer program

Abstract

[Solution] A question sentence generating device is used with a question-answering system, and it includes: word receiving means for receiving a word 480 as a source for generating a question sentence; and question sentence generating database 502 comprised of a plurality of entries for generating a question sentence. Each of the plurality of entries has a word as a key and includes an answer sentence pattern co-occurring with the word, used in the question-answering system. The question sentence generating device further includes a question sentence generating unit 506, searching the question sentence generating database 502 for an answer sentence pattern using the word 480 received by the word receiving means as a key, for generating a question sentence from a retrieved answer sentence pattern and the received word 480.

The invention claimed is: 
     
       1. A question sentence generating device for use with a question-answering system, the question sentence generating device comprising:
 an interface configured to receive a word or a word sequence as a source for generating a question sentence; and 
 a memory including a database comprised of a plurality of records for generating question sentences, wherein:
 each of said plurality of records has a key word and is generated from an answer having an answer sentence pattern co-occurring with the key word; 
 
 a processor configured to:
 using the received word as a key, search and retrieve from said question sentence generating database an answer sentence pattern; 
 generate a question sentence from the retrieved answer sentence pattern and said received word, comprising:
 generating question candidates by (1) transforming the retrieved answer sentence pattern into a plurality of question patterns and (2) combining each of the plurality of question patterns with the received word; 
 scoring each of the question candidates, wherein the score indicates a fit of each question sentence candidate as being a question having as an answer the answer from which the answer sentence pattern is generated; and 
 selecting as the question sentence the question sentence candidate having a best score; and 
 
 output the generated question sentence. 
 
 
     
     
       2. The question sentence generating device according to  claim 1 , wherein:
 the memory additional includes a synonym dictionary configured to store synonymous relation or entailment relation of a word or an answer sentence pattern or both; and 
 the processor is further configured to:
 generate a plurality of question sentences; 
 select distinct ones of said generated plurality of question sentences to generate a smaller number of question sentences by referring to said synonym dictionary; and 
 output the generated smaller number of question sentence. 
 
 
     
     
       3. The question sentence generating device according to  claim 1 , wherein:
 the memory additional includes a thesaurus configured to store classification information for classifying words or answer sentence patterns or both systematically in accordance with their meanings; and 
 the processor is further configured to:
 generate a plurality of question sentences; 
 select distinct ones of said generated plurality of question sentences to a smaller number of question sentences by referring to said thesaurus; and 
 output the generated smaller number of question sentences. 
 
 
     
     
       4. The question sentence generating device according to  claim 1 , wherein
 said processor is configured to:
 receive a plurality of words; and 
 search said question sentence generating database, using the received plurality of words, for an answer sentence pattern co-occurring with the received plurality of words. 
 
 
     
     
       5. The question sentence generating device according to  claim 1 , wherein
 said processor is further configured to:
 search and retrieve said question sentence generating database for an answer sentence pattern using the received word as a key; 
 generate a question sentence and an answer sentence to the question sentence from the retrieved answer sentence pattern and said received word; and 
 output the generated question sentence and the generated answer sentence to the question sentence. 
 
 
     
     
       6. The question sentence generating device according to  claim 1 , wherein
 said question-answering system includes a factoid type question-answering sub-system responsive to a factoid type question sentence; 
 said factoid type question-answering sub-system is configured to generate an answer sentence candidate by searching an answer sentence generating database using a key consisting of a pattern of the question sentence and a word or a word sequence included in the question sentence; and 
 said answer sentence generating database and said question sentence generating database include common records generated from the same corpus. 
 
     
     
       7. The question sentence generating device according to  claim 1 , wherein:
 said question-answering system further includes a non-factoid type question-answering sub-system responsive to a non-factoid type question; 
 said non-factoid type question-answering sub-system is configured:
 to extract a plurality of passages as answer sentence candidates from a corpus, 
 to calculate a score indicating fitness as an answer to said given question by using a pre-learned scoring means, and 
 to output an answer sentence candidate having the highest score as an answer to said given question; 
 
 the memory further includes a question sentence database configured to store a plurality of question sentences each generated from any of a set of passages prepared in advance and not explicitly distinguished as a question or an answer and having as an answer a passage as a source of said question sentence; 
 the processor is further configured to:
 receive a second word or a second word sequence as a source of generating a question sentence; 
 generate and output a new question sentence from the received second word or second word sequence as the source of generating the question sentence or synonyms or entailments of these and from a question sentence stored in said question sentence database by referring to said question sentence database; and 
 collectively output the generated question sentence and the generated new question sentence. 
 
 
     
     
       8. The question sentence generating device according to  claim 1 , wherein the scoring of each of the question candidates is performed using a machine learning algorithm. 
     
     
       9. A question sentence generating device for use with a question-answering system, wherein:
 said question-answering system includes:
 a non-factoid type question-answering sub-system responsive to a non-factoid type question, wherein the non-factoid type question-answering sub-system is configured to:
 extract a plurality of passages as answer sentence candidates from a corpus, 
 calculate a score for each passage, said score indicating fitness as an answer to said given question; and 
 output an answer sentence candidate having the highest score as an answer to said given question; 
 
 
 said question sentence generating device comprising:
 a memory including a question sentence database configured to store a plurality of question sentences each generated from any passage in said corpus and having as an answer a passage as a source of generating the question sentence; 
 an interface configured to receive a word or a word sequence; and 
 a processor configured to generate and output a new question sentence from the received word or word sequence as the source of generating the question sentence or synonyms or entailments of these and from a question sentence stored in said question sentence database by referring to said question sentence database. 
 
 
     
     
       10. A computer program stored on a non-transitory computer readable medium causing a computer to function as a question sentence generating device for use with a question-answering system, wherein said computer is connected to a question sentence generating database comprising a plurality of records for generating question sentences, each of said plurality of records having a key word and is generated from an answer having an answer sentence pattern co-occurring with the word, wherein, when executed by a processor, said computer program causes said processor to:
 receive a word or a word sequence as a source for generating a question sentence; and 
 search and retrieve from said question sentence generating database an answer sentence pattern using a key consisting of the received word; 
 generate a question sentence from the retrieved answer sentence pattern and said received word, comprising:
 generating question candidates by (1) transforming the retrieved answer sentence pattern into a plurality of question patterns and (2) combining each of the plurality of question patterns with the received word; 
 scoring each of the question candidates, wherein the score indicates a fit of each question sentence candidate as being a question having as an answer the answer from which the answer sentence pattern is generated; and 
 selecting as the question sentence the question sentence candidate having a best score; and; and 
 
 output the generated question sentence. 
 
     
     
       11. The computer program according to  claim 10 , wherein the scoring of each of the question candidates is performed using a machine learning algorithm.